Means for utilizing waste furnace gases



Patented Feb. 28, 1922.

ATTOPNEY G. A. WITTE.

MEANS FOR UTTLTZING WASTE FURNACE GASES.

APPLICATION HLED APR.8.1919. 1,407,717.

UNITED STATES PATENT OFFICE.

GUSTAV A. WITTE, 0F PHILADELPHIA, PENNSYLANIA, ASSIGNOR TO INTERNA.- TIONAL y:PRECIIEITA'IION COMPANY, OF LOS ANGELES, CALIFORNIA,A CORPO- BATION OF CALIFORNIA.

MEANS FOR UTILIZING WASTE `FUR'NACE GASES.

Application led April 8,

To all whom it 'may concern:

Be it know-n that I, GUsTAvA. WITTE, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Means for Utilizing Waste Furnace Gases, of which the following is a specification.

This invention relates to utilization of gases from furnaces, such as cement kilns, l

or other furnaces, which produce gases having high temperature and containing considerable suspended matter, such as dust and fume.

The main object of the present invention is to provide improved means for utilization of the heat of such gases in the production of steam, the particularobject of my invention in this connection being to so construct such apparatus that its operation will not be interfered with or rendered ineective by reason of the presence of the suspended material in the gases. In waste heat boilers of the water-tube type and comprising non-vertical' water-tubes,as heretofore applied in connection with cement kilns, or other fur-- naces, there has'been a tendency for the'suspended material in the furnace gases to coli lect or deposit on the boiler tubes, such deposits tending to clog the boiler passages and to seriously interfere with the conduction of heat through the boiler' tubes. This is especially objectionable in cases where the deposited material is of such nature that it tends to form an adherent deposit or cake on the boiler tubes. My invention is directed particularly to overcoming this objection by providing for continual self cleaning action, as hereinafter described.

Another object of my invention is to provide for separation or recovery of the suspended material from the gases in such manner that the waste heat boiler used for recovering the heat from the gases is used only for that purpose and does not have to perform the function of recovering any of the suspended material. With this end in view, I provide for maintaining the gas flow through the waste heat Water-tube boiler in such manner as to cause all of the suspended material to be swept through the boiler pas` sages without deposition; andthe gas, after Specification of Letters Patent.

Patented Feb. 2s, 192.2.

1919. serial No. 283,653.

- ferring thereto Fig. 1 is a side elevation `of such apparatus partly in section.

Fig. 2 is a partly-sectional .plan view thereof. v

In Figs. 1 and 2, Fig. 1 designates a furnace, which -may be a rotary cement kiln, said furnace discharging its hot gases into a stack base 2, whose stack 3 is normally shut off by damper 4. A flue 5 leads from the stack base to a waste heat boiler comprisin an enclosing casing 6 and boiler tubes `cooling in this manner, is then subjected to (said boiler-tubes being non-vertical, that is l extendingpat an angle to the vertical direction) and steam drum 8, said boiler tubes and steam drum being connected in any usual or suitable manner for. the generation of steam, and the casing 6 being provided with suitable partitions or bailles for directing the hot flue gases from the flue 5 in contact with said boiler tubes 7. For this purpose I may provide a plurality of vertical partition walls 10 extending from top to bottom of the furnace chamber and dividing the space therein into a plurality of vertical passages 11, 12 and 13. The first passage 11 is connected at its upper end to the inlet flue 5 for the boiler and at its lower end through a lateral opening 14with an upwardly eX- tending duct 15 leading to an opening 16 at the top of the vnext succeeding vertical passage 12. Similarly the vertical passage 12,0pens laterally at 17 at its lower end into a duct 18 extending upwardly from said opening and communicating through opening 19 at its upper end with the u per end of the vertical pasasge 13. Vertica passage 13 is shown as connected at its lower end to an outlet flue 20. It'is to be understood, however, that any desired number of the vertical passages referred to may be used, each communicating at its lower end with an outside duct leading to the top of the next succeeding vertical passage and the last passage in the series belng connected to the outheat boilers yfor .the whole plant.

let due.. lt is also to be understood that the passages referred to are not necessarily vertical so long as they extend in such direction that the gases passing through same are directed downward against the boiler tubes.

The outlet flue 20 is connectedto suitable means for drawing the gases through lthe waste heat boiler.. For reasons hereinafter explained, it is preferred to' effect this operation in such manner that the gases pass through the boiler at comparatively high velocity and l, therefore, prefer to employ forced draft Jfor this purpose, a fan or blower 22 being connected to receive the gases from the outlet :due 20 and discharge the gases to any suitable means, for'example, to means such as a dust separator 23, for separating or removing the suspended material therefrom before the gases are discharged into the atmosphere. 1

inthe operation of waste heat boilers in connection with cement kiln, or other furnaces, a difficulty has arisen on account of the ductuation in the amount of heat supplied by the waste heat gases of the furnaces as compared with the amount required for power generation in connection with the installations of which such furnaces form a part. ln order to overcome this ditiiculty, l provide an. auxiliary boiler, or boiler plant, indicated at 24, fired or heated by separate furnace means, indicated at 25, and

supplying steam through a pipe 26 to the same outlet pipe 27, which receives the.

steam through pipe 28 from the steam drum 8 of the waste heat boiler aforesaid. ln installations of any considerable size there will be a plurality of the kilns or furnaces 1, and, preferably, a corresponding number of the waste heat boilers 6, and a single auxiliary boiler plant may be used in connection with the battery of waste This auxiliary boiler being separately fired may be varied in its'output by proper adjustment of the ring thereof, so as' to alwaysy provide sufficient steam to make up a given amount, or the amount required by the power installation, irrespective of liuctuations in the operation of the furnaces or kilns.

In the operation of the apparatus, the hot kiln gases are drawn from the flue 5 through the successive passages of the waste heat boiler, the hot gases passing downwardly through each of the .1 ssages 11, 12 and 13, successively, and upwardly through the ducts on lthe outside of the boiler, so that in every case where thefnot gases are passing in contact with the boiler tubes their movement is in a downward direction. l have found that und `4r these conditions there is no tendency for the solid materials suf-- pended in the gases to deposit or cake on the boiler tubes, so that the boiler may be vthe spaces directly above the tubes and away froml the direction ofthe oncoming stream of gas constituting quiescent or suction zones in which the material settles and is then retained by gravity on the horizontally extending ledges or support offered b the upper faces of the tubes; but this enect does not occur in those passages where the gases pass downward, the face or part of the tubes which is away from the oncoming stream of gas beinef on the lower side of the tubes and, therefore, not presenting a ledge on which the material can be retained by gravity, while, on the other hand, the parts or faces of the tubes which are exposed to impact or attrition by the oncoming stream of gas are swept clear `and clean by said impact and attrition. In order to accentuate this effect and insure the sweeping of the suspended material through t holler without deposition, I prefer to force the gases at more than the usual velocity through the boiler, the partition walls being made of sufficient numben and with properly restricted passages.y to insure the required speed of the gases. In this connertion, the fact that the gases pass athigh velocity and carry solid suspended materlal gives rise to a bombarding action on the boiler tubes, which tends to scour or cut away any cake that may tend to form on the boiler tubes, thereby aiding in the self cleaning action. p

In order to utilize as much of the heat as possible, it is preferable to connect the waste heat boiler or boilers directly to the stack base of the kiln. Said stack base, however, serves in the usual manner to collect more or less of the coarser dust and, if desired, it may be made suiiiciently large or may be provided with an auxiliary chamber extension to insure retention of any desired amount of the coarser dust. The ases after having passed through the waste ieat boiler are sufficiently cooled to enable them lto be treated by any suitable means for the col lection of any suspended material therein, for example, they may be passed through the dust separator 23 wherein they are subjected to any well known dust separating operation for collection of dust and fume therefrom. In' the case of cement kiln gases the material so collected contains, in general, a considerable portion of potassium compound, and constitutes a valuable product.

What I claim is:

Awase heat boiler for utilizing the heat of furnace gases containing suspended material, comprising a casingl` boiler tubes mounted therein and formed as non-vertical Water tubes, vertical Walls Within said' casing dividing the space within the casing into a series of vertically extending passages, an external connection from the lower part of each of said passages to the upper part of the next succeeding passage, and inlet and outlet connections for the first and last of said passages whereby the hot gases are caused to pass downwardly in each of said passages in Contact with the boiler tubes extending therein.

In testimony whereof I have hereunto subscribed my name this 31st day of March, 20

GUST'AV A. WITTE. 

